The following account of the prior art relates to one of the areas of application of the present application, hearing aids.
Originally, wireless or wired electrical inputs to hearing aids were typically used to provide an amplified version of a surrounding acoustic signal. Examples of such systems providing an electric input could be telecoil systems used in churches or FM system used in schools to transmit a teacher's voice to hearing aid(s) of one or more hearing impaired persons.
In recent years, mobile communications has created a new situation where the electrical input signals can be totally unrelated to the surrounding audio environment. This allows for example a wearer of a hearing instrument to listen to music or talk on the phone, e.g. using telecoil or digital near field or far field radio systems.
In the latter situation the surrounding audio environment can interfere with the perceived audio quality and speech interpretation, if e.g. the listener is in a noisy environment.
This problem has historically been addressed in hearing aids by having two programs available for each type of electrical input, one for use in a noisy environment with only the electrical input (microphone off), and one for other use with both the electrical input and the hearing aid microphone(s) on.
Such solution solves the general problem. However, the user still has problems, if he/she is in a noisy environment and needs to address persons in their proximity, while receiving a direct electric input. If a wearer leaves the microphone(s) off, he/she will not be able to communicate with persons in the near proximity, and if he/she leaves the microphone(s) on, the signal to noise ratio (S/N) of the combined signal may be too low to allow him/her to understand the electrical input signal.
EP 1 691 574 A2 and EP 1 691 573 A2 describe a method for providing hearing assistance to a user of a hearing instrument comprising receiving first audio signals via a wireless audio link and capturing second audio signals via a microphone, analyzing at least one of the first and second audio signals by a classification unit in order to determine a present auditory scene category from a plurality of auditory scene categories, setting the ratio of the gain applied to the first audio signals and the gain applied to the second audio signals according to the present determined auditory scene category and mixing the first and second audio signals according to the set gain ratio in the hearing instrument.